Katherine Grainger admitted there was 'work to do' after missing a medal at the final rowing World Cup regatta of the season.

The three-time Olympic silver medallist was forced to settle for fourth as Mirka Knapkova of the Czech Republic won gold.

Scot Grainger, in her first season in singles sculls - won the opening world cup round in Spain and finished fourth in Munich three weeks ago.

But Lucerne was the toughest field she has yet faced, with 22 of the world's top women scullers present.

"On balance I'm disappointed. But there are technical improvements I can make," she said.

"I've still been making good progress since Munich.

"Coming into the singles, I wanted to learn, and see how fast I was, but this has never been just about winning, it's the whole competition."